A diffusion-cooled CO2 laser is a gas-discharge laser in which cooling of the discharge occurs by having a small separation between cooled electrodes forming the discharge. The separation is sufficiently small that there is a high probability excited state CO2 molecules residing in a relatively long lifetime “010” bending vibration state (a non-lasing state only marginally above the ground state), can collide with the cooled electrodes. This collision process depopulates the “010” state and prevents a “population bottle neck” from developing. The depopulation of the “010” lower level, increases the population inversion in the upper “lasing” level which leads to higher laser output power and efficiency.
In such a low power laser it is usual to mount resonator mirrors of the laser as an integral part of a laser-housing. When mirrors are mounted in this way, it is important to minimize bending of the laser housing, because such bending could cause pointing of an output beam to vary with temperature.
One prior-art approach to minimizing bending of a diffusion-cooled CO2 laser-housing has involved the use of a flexible housing with cooling as symmetrical as possible. Arrangements using this approach are described in U.S. Pat. No. 4,787,090 and U.S. Pat. No. 6,192,061, both assigned to the assignee of the present invention. Arrangements using a similar approach are also described in U.S. Pat. No. 6,198,758 and U.S. Pat. No. 6,983,001. While all of these arrangements have been successful to some degree, it is believed that none of the arrangements has an optimum level of actual cooling, symmetry of cooling, and flexibility of the laser housing.